1. Field of the Invention
The present invention relates to a stator core which is used in a rotary electric machine such as an electric motor or the like. It also relates to a method of assembling the stator core as well as to that apparatus for assembling the stator core which is used in carrying out the method.
2. Description of the Related Art
As can be seen in Japanese Published Unexamined Patent Application No. 124241/1986, there is conventionally known the following stator core. Namely, a segmented (or divided) core is made up of an arcuate yoke portion, a pole portion which extends diametrically inwards from the yoke portion, and a tooth portion on a diametrically inner end of the pole portion. On one circumferential end and on the other circumferential end of the yoke portion, there are formed a projection and a concave groove (hereinafter simply called a groove), respectively. A plurality of segmented cores each being formed as described above are circumferentially connected together (i.e., connected together in the circumferential direction) such that a projection of one of adjoining segmented cores is fit into a groove of the other of the adjoining segmented cores, thereby assembling a stator core.
In the above-described conventional stator core, the groove is formed into a dovetail groove and the projection which is formed into a dovetail shape is fit by pressing into the groove in an axial direction of the stator core.
Since the stator core is relatively large in its axial length, in the above-described conventional one in which the projection is fit into the groove in the axial direction, the stroke of press fitting becomes long. In order to prevent the load of press fitting from becoming excessive, the interference between the projection and the groove must be made small. As a result, the segmented cores are likely to give rise to plays or are likely to cause rattling among them.
The present invention has a first object of providing a stator core in which this kind of disadvantage has been eliminated.
Further, in the above-described conventional stator core, the work of subjecting the segmented cores to press fitting in the axial direction must be carried out in sequence one at a time. It has therefore a disadvantage in that the stator core takes much time assemble.
In view of the above-described disadvantage, the present invention has a second object of providing a method of assembling the stator core with a good working efficiency as well as of providing an apparatus for assembling a stator core which is used in carrying out this method.